1. Field of the Invention
The present invention relates to the field of producing fiber reinforced thermoplastic materials, and more particularly to methods and apparatus for increasing the transverse tensile strength of such materials while substantially reducing the amount of breakage of the fibers in such materials.
2. Prior Art
U.S. Pat. No. 4,680,224 assigned to the Phillips Petroleum Company, the complete disclosure of which is hereby incorporated by reference, broadly discloses a prior process for porducing fiber reinforced thermoplastic material in the form of tape by a process known as "pultrusion". While the apparatus and process disclosed in this patent has successfully produced commercial fiber reinforced thermoplastic impregnated tape, and laminates and other composites produced from such tapes, a problem has been encountered with the degree of breakage of the filaments or fibers as they pass through the bath in which the fibers are impregnated and coated with the thermoplastic resin. In addition, the transverse tensile strength of the impregnated fiber coated tape has not been as high as is currently desired for certain applications such as in the aerospace field where portions of aircraft are fomed from laminates or composites which are made from the fiber reinforced thermoplastic tape produced by this prior art process.